In such an installation for producing electrical or mechanical energy from hydraulic energy, one of the difficulties is controlling the level of oxygen dissolved in the water discharge pipe. For ecological reasons, this oxygen level must not be less than a minimum threshold in order to respect the aquatic environment downstream of the installation.
However, it is difficult to control this oxygen level since it varies during the course of the seasons. Thus, winter water has a tendency to be laden with oxygen since it generally comes from snow melt. On the other hand, in summer, often the water stagnates upstream of the installation and has a level of dissolved oxygen that is generally too low with respect to the minimum threshold.
U.S. Pat. Nos. 2,300,748 and 4,142,825 concern a hydraulic installation including a discharge pipe for discharging a flow of water discharged from a turbine. The inside of the discharge pipe is equipped with hollow ribs. A conduit brings pressurized air inside the ribs. This air is injected into the water at the discharge from the turbine by means of holes pierced in the ribs. These devices require the use of an auxiliary apparatus for injecting compressed air into the ribs.
It is this drawback that the invention sets out particularly to remedy by proposing a fin intended to be installed projecting inside a discharge pipe of a hydraulic machine.